Andrew Mills/The Star-LedgerCrowded beach scene looking south from the 15th Avenue beach in Belmar. A national report has ranked New Jersey second behind New Hampshire for the best beach water quality.

Dry sunny days bring more tourists to the Jersey Shore and, according to a national report, those beachgoers enjoyed some of the cleanest waters in the nation last year.

Beat only by New Hampshire, New Jersey ranked second in the country for beach water quality last year, according to a report released today by the Natural Resources Defense Council.

But environmentalists caution against claiming victory over problems that contributed to poor water quality in the past. The high ranking, they said, is a result of a dearth of rainy days last summer to wash pollutants into the oceans.

"In 2010, New Jersey’s beaches had a very good report card — but only because it hardly rained at all,’’ said Heather Saffert, a scientist for Clean Ocean Action. "The data shows that when it rains, pollution often pours into our waterways and threatens public health.’’

The NRDC’s annual report, "Testing the Waters: A Guide to Water Quality at Vacation Beaches,’’ analyzed government data on testing results last year at more than 3,000 locations throughout the country. Among its criteria, it measured beaches on the number of days closed.

In New Jersey, there were 109 beach closures and advisories last year, compared to 180 in 2009, with only 2 percent of the hundreds of water quality tests exceeding the state’s allowable levels for fecal bacteria. The previous year that figure was 5 percent.

Of all the closures last year, 25 were from high bacteria levels and 77 were preemptive measures at six beaches in Monmouth County where heavy rainfall almost always raises the bacteria levels to unacceptable levels.

The beaches with the fewest number of closings were in Atlantic and Cape May counties, where Saffert said fewer outfall pipes direct stormwater to the ocean and.

The worst beach in New Jersey — Beachwood Beach West on the Toms River in Beachwood — earned national distinction by appearing on the debut of the NRDC’s "repeat offender’’ list of beaches exceeding daily maximum bacterial levels five years in a row. The only beach from New Jersey to make that list, Beachwood West joins six beaches in California, two in Wisconsin and one each in Florida, Illinois, Ohio and Texas.